This invention relates to organometallic compounds of metals of Groups VIIb, VIII, IX, and X including manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum and their uses in chemical vapor deposition (CVD) methods for depositing films of metal or metal derivatives on a substrate or forming a metal or metal derivative in powder form. More particularly the invention relates in preferred aspects to organometallic precursor compounds derived from metals of Groups VIIb, VIII, IX, and X especially suited for high purity deposition of the metal or a derivative such as, for example, a metal silicide, utilizing CVD techniques.
Metal silicides derived from metals of Groups VIIb, VIII, IX, and X are attractive compounds in the electronics field particularly regarding the manufacture of integrated circuits and micro-electronics. Interest in metal suicides is increasing as device scale-down progresses due to its good thermal and chemical stability, low resistivity, wide process window and its small lattice mismatch to the silicon crystal lattice, which allows the metal silicide to be grown epitaxially on silicon. Furthermore, the metal films derived from metals of Groups VIIb, VIII, IX, and X selectively deposited on silicon substrates can be made to form self-planarized epitaxial metal patterns whose surfaces are atomically flush with the surrounding silicon.
CVD is a particularly useful technique for deposition of metal and metal silicide films as compared to other methods of deposition such as plasma vapor deposition (PVD) methods like sputtering, e-beam evaporation, molecular beam epitaxy, and ion beam implantation. CVD can also be used to provide flexibility in the design of manufacturing electronic devices including the potential to reduce the number of processing phases required to provide a desired product.
To date, CVD of various metals has been hampered by the lack of suitable precursor compounds. For example, conventional cobalt organometallic CVD precursors, such as Co(C5H7O2)2, Co(C5H7O2)3, Co2(CO)8, CO(C5H5)2. Co(C5H5)(CO)2 and Co(CO)3(NO) have not demonstrated satisfactory properties for use in forming device-quality cobalt silicide films. Co(C5H7O2)2 and Co(C5H7O2)3 have low vapor pressures and therefore require high temperatures to produce a vapor flow sufficient to support CVD. Co2(CO)8 is significantly more volatile and can produce cobalt metal coatings without the addition of a reducing agent, but is too thermally unstable to be a practical CVD precursor, giving rise to competing side reactions and decomposition during storage, even under vacuum or an inert atmosphere. Co(C5H5)2 and Co(C5H5) (CO)2 may be used to deposit cobalt films, but such films can be subject to severe carbon and oxygen contamination problems, even when H2 is used as a reducing agent. Likewise, Co(CO)3(NO) can be subject to unacceptable contamination with carbon and oxygen in the resulting cobalt and cobalt silicide layers when deposition is conducted at less than 350xc2x0 C. or with a hydrogen flow of less than 500 standard cubic centimeters (sccm). Organometallic precursors based on the other metals in Groups VIb, VIII, IX, and X have demonstrated similar shortcomings.
Therefore there remains a need in the industry for precursor compounds derived from metals of Groups VIb, VIII, IX, and X suitable for CVD that can produce high purity, device-quality films of metals and/or metal derivatives such as, for example, metal silicide films. The present invention provides organometallic compounds which are well suited for such uses.
It is one object of the present invention to provide organometallic precursor compounds suitable for the chemical deposition of metals such as those of Groups VIIb, VIII, IX, and X. It is an object to provide preferred organometallic compounds of metals of Groups VIIb, VIII, IX, and X with relatively high vapor pressures and good thermal stability such that they are vaporizable without substantial decomposition. It is an object of one embodiment of the present invention to provide preferred organometallic compounds lacking metal-carbon bonds, which are suitable for use in chemical vapor deposition methods, whereby high purity metals or metal derivatives such as for example, metal suicides may be formed.
It is one object of another aspect of the present invention to provide novel organometallic compounds having relatively high vapor pressures and good thermal stability such that they are vaporizable without substantial decomposition.
It is one object of yet another aspect of the present invention to provide chemical deposition methods to deposit films of metal or metal derivatives derived from metals of Groups VIIb, VIII, IX, and X on various substrates, including silicon and gallium arsenide (GaAs) among others and to form metal and metal derivatives in powder form. It is an object of this aspect of the invention to provide preferred methods of producing metals and metal derivatives such as, for example, metal silcide as films of high purity, which particularly avoid contamination of the films by carbon and/or oxygen. It is a further object of this aspect of the present invention to provide preferred CVD methods useful in the fabrication of device-quality films based on metals of Groups VIIb, VIII, IX, and X or the metal""s derivative, such as for example, a metal silicide or metal oxide.
Various of these and other objects are achieved by the organometallic phosphite and phosphine compounds according to the present invention and their use in deposition methods.
In one aspect of the present invention, films of metal and metal derivatives such as, for example, silicide are provided by the chemical deposition of metal or metal containing material on a substrate by contacting the substrate surface with an organometallic compound containing a Group VIb, VIII, IX or X metal and having the general formula I
(R1)mM(PR23)xxe2x80x83xe2x80x83I
where M is a metal selected from a Group VIIb, VIII, IX or X metal wherein (a) when M is manganese, technetium or rhenium, m is 1; x is 5 and m+x is 6; (b) when M is iron, ruthenium or osmium, m is 0, 1, 2, 3 or 4; x is 2, 3, 4 or 5 and m+x is 4, 5, 6 or 7; (c) when M is cobalt, rhodium or iridium, m is 1, 2, 3 or 4 and x is 2, 3 or 4 and m+x is 4, 5, 6, 7 or 8; and (d) when M is nickel, palladium or platinum, m is 0 or 2, x is 2, 3 or 4 and m+x is 2, 3, 4, 5 or 6; each R1 is independently selected from the group consisting of hydrogen, deuterium, N2, H2, D2 and a group of the formula xe2x80x94CR32xe2x80x94CR32xe2x80x94R4; each R2 is independently selected from the group consisting of lower alkyl, aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy, alkylsilyl, arylsilyl, arylalkylsilyl, alkoxysilyl, aryloxysilyl, arylalkoxysilyl, alkylsiloxy, arylsiloxy, arylalkylsiloxy, alkoxysiloxy, aryloxysiloxy, arylalkoxysiloxy, alkylsilylalkyl, arylsilylalkyl, arylalkysilylalkyl, alkoxysilylalkyl, aryloxysilylalkyl, arylalkoxysilylalkyl, alkylsiloxyalkyl, arylsiloxyalkyl, arylalkylsiloxyalkyl, alkoxysiloxyalkyl, aryloxysiloxyalkyl, arylalkoxysiloxyalkyl, alkylsilylalkoxy, arylsilylalkoxy, arylalkylsilylalkoxy, alkoxysilylalkoxy, aryloxysilylalkoxy arylalkyloxysilylalkoxy, alkylsiloxyalkoxy, arylsiloxyalkoxy, arylalkylsiloxyalkoxy, alkoxysiloxyalkoxy, aryloxysiloxyalkoxy, and arylalkoxysiloxyalkoxy; each R3 is independently selected from the group consisting of hydrogen, deuterium, C1-C6 alkyl, C1-C6 cycloalkyl, phenyl, benzyl, (C1-C2 alkyl or alkoxy)3-silyl, and (C1-C2 alkyl or alkoxy)3-siloxy and wherein at least two groups R3 are selected from the group consisting of hydrogen and deuterium; R4 is hydrogen or deuterium; and wherein when M is cobalt, rhodium or iridium and one group R1 is selected to be N2, then m is 2 and the second group R1 is hydrogen or deuterium. The preferred organometallic compounds of this embodiment of the invention are volatile and have good thermal stability in CVD processes, in that they can be vaporized without substantial decomposition.
In one aspect of the present invention, powders containing metal and/or metal derivatives are provided by the chemical decomposition of organometallic precursors upon dispersing a vapor or liquid into the medium, the vapor or liquid containing an organometallic compound of the formula (R1)mM(PR23)x, where M is a metal selected from a Group VIIb, VIII, IX or X metal wherein (a) when M is manganese, technetium or rhenium, m is 1; x is 5 and m+x is 6; (b) when M is iron, ruthenium or osmium, m is 0, 1, 2, 3 or 4; x is 2, 3, 4 or 5 and m+x is 4, 5, 6 or 7; (c) when M is cobalt, rhodium or iridium, m is 1, 2, 3 or 4 and x is 2, 3 or 4 and m+x is 4, 5, 6, 7 or 8; and (d) when M is nickel, palladium or platinum, m is 0 or 2, x is 2, 3 or 4 and m+x is 2, 3, 4, 5 or 6; each R1 is independently selected from the group consisting of hydrogen, deuterium, N2, H2, D2 and a group of the formula xe2x80x94CR32xe2x80x94CR32xe2x80x94R4; each R2 is independently selected from the group consisting of lower alkyl, aryl, arylalkyl, alkoxy, aryloxy, arylalkoxy, alkylsilyl, arylsilyl, arylalkylsilyl, alkoxysilyl, aryloxysilyl, arylalkoxysilyl, alkylsiloxy, arylsiloxy, arylalkylsiloxy, alkoxysiloxy, aryloxysiloxy, arylalkoxysiloxy, alkylsilylalkyl, arylsilylalkyl, arylalkysilylalkyl, alkoxysilylalkyl, aryloxysilylalkyl, arylalkoxysilylalkyl, alkylsiloxyalkyl, arylsiloxyalkyl, arylalkylsiloxyalkyl, alkoxysiloxyalkyl, aryloxysiloxyalkyl, arylalkoxysiloxyalkyl, alkylsilylalkoxy, arylsilylalkoxy, arylalkylsilylalkoxy, alkoxysilylalkoxy, aryloxysilylalkoxy arylalkyloxysilylalkoxy, alkylsiloxyalkoxy, arylsiloxyalkoxy, arylalkylsiloxyalkoxy, alkoxysiloxyalkoxy, aryloxysiloxyalkoxy, and arylalkoxysiloxyalkoxy; each R3 is independently selected from the group consisting of hydrogen, deuterium, C1-C6 alkyl, C1-C6 cycloalkyl, phenyl, benzyl, (C1-C2 alkyl or alkoxy)3-silyl, and (C1-C2 alkyl or alkoxy)3-siloxy and wherein at least two groups R3 are selected from the group consisting of hydrogen and deuterium; R4 is hydrogen or deuterium; and wherein when M is cobalt, rhodium or iridium and one group R1 is selected to be N2, then m is 2 and the second group R1 is hydrogen or deuterium. The preferred organometallic compounds of this embodiment of the invention are volatile and have good thermal stability in CVD processes, in that they can be vaporized without substantial decomposition.
xe2x80x9cOrganometallicxe2x80x9d means a compound having at least one metal atom and at least one organic moiety. xe2x80x9cOrganic moiety,xe2x80x9d as used herein, means a portion of a molecule bonded to the remainder of the molecule, and including at least one carbon atom.
Preferred embodiments include, but are not limited to, depositing a metal film on an integrated circuit device work piece. Films comprised of metal derivatives, such as for example, a metal silicide, may be formed by annealing such metal films after deposition on the substrate, or alternatively, by conducting chemical vapor deposition with a mixture of a metal compound according to the present invention and one or more silicon chemical vapor deposition precursor compounds. Such metal and/or metal silicide films can be selectively deposited on an integrated circuit work piece to provide electrically conductive contacts on the work piece.
In preferred embodiments of the present invention:
a.) R1 is hydrogen or deuterium, or,
b.) m is 0.
The metal hydrides of these preferred embodiments advantageously lack metal-carbon bonds.
In another preferred embodiment, novel organometallic phosphite and phosphine compounds of formula I are provided wherein groups R2 are not all the same moiety. In another preferred embodiment, at least one of groups R2 contain a silicon atom, as for example, but without limitation, when R2 is alkylsilyl, arylsilyl, arylalkylsilyl, alkoxysilyl, aryloxysilyl, arylalkoxysilyl, alkylsiloxy, arylsiloxy, arylalkylsiloxy, alkoxysiloxy, aryloxysiloxy, arylalkoxysiloxy, alkylsilylalkyl, arylsilylalkyl, arylalkysilylalkyl, alkoxysilylalkyl, aryloxysilylalkyl, arylalkoxysilylalkyl, alkylsiloxyalkyl, arylsiloxyalkyl, arylalkylsiloxyalkyl, alkoxysiloxyalkyl, aryloxysiloxyalkyl, arylalkoxysiloxyalkyl, alkylsilylalkoxy, arylsilylalkoxy, arylalkylsilylalkoxy, alkoxysilylalkoxy, aryloxysilylalkoxy arylalkyloxysilylalkoxy, alkylsiloxyalkoxy, arylsiloxyalkoxy, arylalkylsiloxyalkoxy, alkoxysiloxyalkoxy, aryloxysiloxyalkoxy, and arylalkoxysiloxyalkoxy.
In another aspect of the present invention, chemical deposition methods are provided for depositing metal, metal oxide and/or metal silicide films on a substrate by contacting the substrate surface with at least one metal precursor compound according to the present invention with the surface heated to a temperature at or above which the metal compound reacts to provide the film. In one embodiment of this aspect, the surface is heated to a temperature at or above the thermal decomposition temperature of the organometallic compound. In another embodiment, the surface facilitates the decomposition reaction of the organometallic compound at a temperature below the thermal decomposition temperature of the organometallic compound.
The metal precursor compounds of the present invention may also be adapted to liquid state chemical deposition methods as well as any known CVD method, with the conditions for a given application depending on the precursor compound used, the substrate being coated, and the thickness of metal film desired. For liquid phase delivery of metal compounds of the present invention, liquid metal precursor compounds can be delivered to the substrate surface neat or in a solvent compatible with the compound and substrate. Solid metal precursor compounds can be delivered in similarly compatible solvents. Any known liquid application methods can be adapted for use with the present metal compounds, including atomization and other liquid spray techniques.
In CVD methods, inert carrier gases and/or reducing agents, as for example, but without limitation, hydrogen may optionally be used with the present metal compounds in CVD methods. In preferred embodiments, device quality metal or metal silicide films may be produced.
Spray pyrolysis and the techniques described above can also be used without a substrate to deliver the precursor compounds into a medium such as nitrogen at a sufficient temperature to cause the formation of metals or metal derivatives in powder form. The metal powders produced in this manner, like the films deposited on substrates, are suited for high purity applications.
Related objects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.